Mitigating single event effects (SEEs) is becoming increasingly important as advances in integrated circuit (IC) technology reduce feature sizes and power requirements. Mitigating SEEs is especially important for mission-critical applications, because an SEE could jeopardize an entire mission. For example, ICs deployed in spacecraft applications are more susceptible to the high-energy particles that cause SEEs. An SEE in a mission-critical IC of the spacecraft could cause a total failure of the spacecraft, which took a sizable investment to design, build, and launch.
SEEs may range from soft errors that are transient or correctable, to hard errors that are not correctable or that may permanently damage an IC. An SEE is generally classified as a single event upset (SEU), a single event burnout (SEB), or a single event latchup (SEL). An SEU is a transient, soft error, and is non-destructive and is caused by a charged particle passing through an IC leaving a wake of electron-hole pairs.
An SEB can cause permanent failure of an IC due to a high current state in a transistor. For example, a power MOSFET biased in the OFF state (i.e., blocking a high drain-source voltage) can suffer an SEB when a heavy ion passing through the MOSFET deposits sufficient charge to turn the device on.
An SEL is a hard error that can potentially destroy an IC. Latchups can be caused by heavy ions or by protons in a sensitive device. An SEL occurs when the vertical and lateral parasitic bipolar junction transistors (BJTs) of a device are activated by an ion strike. Activation of both the vertical and lateral BJTs results in an abnormally high operating current in the device. The ion-induced high current can permanently disable a device if the SEL is not quickly detected and cleared. Cycling power off and on can restore the device to normal operation if the device has not already been permanently damaged. However, in some applications cycling power to the device may result in significant device down time and therefore be unacceptable.